GB2194107A - Electronic kettle - Google Patents

Abstract

Biasing circuits R3, R8 and R4, R10 produce substantially constant currents through diodes SD1, SD2 which are respectively located to sense steam and a dry kettle condition. A further diode DS provides an ambient temperature compensated reference signal to water boiling sensing comparator OA1 and to dry kettle sensing comparator OA2, occurrence of either of the two sensed starts causing a comparator OA3 to provide a high output which turns on an LED D8 and transistors T1, T2 whereby a triac TR1 turns off to de-energise the heater 12. Comparator OA3 is maintained in its high state by a batch NOR1, NOR2 which can be reset by a switch SW1 or by disconnection of the kettle from the A.C. supply AB. A delay circuit D6, R13, C2 prevents comparator OA3 from becoming latched during initial powering up of the circuitry. The latch also causes an electronic buzzer NOR3, NOR4, CR1 to operate until turned off by a timer R15, C3, OA4. The buzzer can be disabled by opening a switch SW2. An input to the timer from comparator OA2 causes the buzzer to operate for a relatively long period if a dry kettle is sensed. <IMAGE>

Description

SPECIFICATION Electronic kettle This invention relates generally to electrically powered kettles for boiling water, and more specifically, to measures for ensuring safe operation of such kettles, as when water reaches a boiling temperature or when a dry kettle is plugged into a line source.

In the prior art, electric kettles have commonly been provided wih thermostatic switches which serves to cut off power when water boils. Such switches are relatively cumbersome devices.

Also, their mode of operation has been such that prior kettles tend to continuously cycle up to a boiling temperature, if they are left plugged into a line source, and there is the distinct possibility of running such a kettle dry. There would also be a tendency for on-off cycling of the kettle to continue once it has run dry and this represents a particularly hazardous mode of operation.

In one aspect, the invention provides a kettle having an electric heating element which is shut off automatically in response to high temperatures at a predetermined location in the kettle. The kettle comprises switching means for regulating the application of electric power to the heating element, a diode attached to the kettle proximate to the predetermined location where the high temperatures are expected to occur, and biasing means for producing a substantially constant current in the diode such that a diode voltage is generated which varies inversely with the temperature of the diode. Means are provided for causing the switching means to assume a non-conductive state in which no electric power is supplied to the heating element when the diode voltage exceeds a reference level.A reference signal for such purposes is preferably provided by a reference diode, also biased to conduct a substantially constant current such that a reference diode voltage is generated which varies inversely with its temperature, but normally exposed to ambient temperatures.

The low level signal changes occuring in diodes to be used as temperature sensors in kettles would normally lead one to expect that diodes would be inappropriate for such applications, as the signals would affected by offset voltages, offset currents and manufacturing tolerances expected of associated electronic circuit components. However, it will be apparent from the teachings of this specification that such is not in fact the case.

In another aspect, the kettle is provided with resettable latching means which cause the switching means to remaining in a non-conductive state once turned off thereby preventing continuous on-off cycling of the kettle when the high temperatures momentarily drop. Other inventive aspects of the present kettles will be apparent from a description of a preferred embodiment below and will be more specifically defined in the attached claims.

The invention will be better understood with references to drawings illustrating a preferred embodiment in which: Figure 1 diagrammatically illustrates principal components of an kettle; Figure 2 is schematic diagram of various circuit components associated with the kettle Reference is made to Fig. 1 which illustrates the overall configuration of a kettle 10 embodying various inventive features. The kettle 10 has a conventional heating element 12. A sensing diode SDI is positioned so as to be exposed to steam produced by water boiling in the kettle and serves to detect and indicate such boiling. A second diode SD2 is positioned proximate to the heating element such that the diode SD2 is exposed to high temperatures associated with the heating element when the kettle 10 is operated dry.Various electronic components associated with the kettle 10 are mounted in an insulting handle 12 and are described in detail below.

The kettle 10 comprises a power supply for operating the electronic components. A resistor R1, diode D1 and capacitor C1 serve to half-wave rectify and smooth an AC line voltage applied at terminals A, B. A resistor R2 and zener diode Z1 are series connected across the capacitor C1, producing at their junction a voltage of about 14 volts. A light emitting diode (LED) D2 provides a visual indication that the kettle is plugged in. The maximum current drawn by the circuit is less than 15 mA. To supply this together with about 2mA bias current for the zener diode Z1 requires R1 to be approximately, neglecting R2 which is much smaller than R1, 2.2 k Ohms. The power dissipated in R1 is approximately 0.65 Watts.The capacitor is sized to achieve less than 1.5 volt peak-to-peak ripple during the negative input half cycle when it must supply all the circuit energy. This value may be calculated in a conventional manner and may nominally be 100 ,uF.

The two temperature sensing diodes SD1, SD2 are biased by resistors R3, R4, respectively.

Each temperature sensor is a semiconductor diode and any diode if properly biased will perform the same task. The bias currents are in the order of about 140 ,uA creating a forward voltage drop of about 530 mV at room temperature. With a constant bias current, the diode voltage, namely, the voltage across the silicon PN junctions associated with the diodes SD1, SD2 varies inversely with temperature, approximately 2 mV per degree Celsius. Thus a 50 degree Celsius temperature rise will decrease the voltage across each diode by about 100 mV.

The circuit comprises four operation amplifiers which are available as a single integrated circuit (IC) package. These operational amplifiers have been designated OA1, OA2, OA3, OA4 in Fig. 2.

The amplifiers OA1-OA3 are operated essentially open loop, although feedback may be provided in the OA3 by latching circuitry described more fully below. The amplifiers OA1 and OA2 function essentially as comparators, and the amplifier OA2 serves essentially as an OR gate producing the logical OR value of the output signals generated by the amplifiers OA1, OA2.

Since the open loop gain for such amplifiers is commonly guaranteed to exceed 15 V/mV, a voltage of 1 mV between the inverting and non-inverting terminals of the amplifiers will drive the output terminal to O or 12.5 volts depending on the polarity of the driving voltage. When the voltage difference between the non-inverting input terminal of the amplifiers exceeds the voltage at the inverting input terminal by a maximum offset voltage of plus or minus 9 mV, plus an error voltage of less than 1 mV, the output will swing within 1.5 volts of one of the supply voltages.

The offset voltage drift is a maximum of 30 nV/degree C. Thus, an operating temperature range of 22 degrees C., plus or minus 10 degrees C., will change the offset voltage by 0.3 mV.

The operational amplifier input bias current has a maximum rated value of .5 uA with an input offset current of plus or minus 0.15 uA. The Thevenin resistance seen by the inverting terminal of OA 1 is approximately R8. A change in the bias current of .15 nA will thus change the voltage by less than 1 AV and can be neglected.

Thus, in the worst case, a differential voltage of 9 mV+.3 mV between the inverting and noninverting terminals will change the output signal of one of the operational amplifiers from 0 volts to 12.5 volts or vice versa. Thus the comparators will discriminate a temperature difference of maximum 9.3 mV/2 mv/degree C. or 4.7 degrees C. on a circuit to circuit variation. Whereas on any specific circuit the comparator will switch for a maximum of .3 mV/2 mV per degree C or .15 degrees C., because of the low cost comparator used and the temperature effects thereupon.

The tolerances in the resistive value of resistors R4, R5 and R8 is nominally 5% and can vary the error voltage occurring between the terminals of the operational amplifiers at room temperature. A 5% reduction in R4 will increase the bias current by about 5% which will increase the diode drop by less than 1.2 mV. An increase in the voltage drop across R8 will be about 10% for a 5% increase in resistor R8, or 7.8 mV. With a worst case combination increase in the value resistive value of resistor R5 the voltage drop across diode D5 be reduced by 1.2 mV.

Thus resistor component tolerances can provide an error voltage variation of up to 7.8+1.2+1.2=10.2 mV. or an additional 5.1 degrees C variation in the worst case on a circuitby-circuit basis.

The variation in forward voltage drop from one diode to another at a specific forward current is not expected to vary by more than about 10 mV from diode to diode within the same batch.

This accounts for a 5 degree C temperature difference.

A 10% variation in the supply voltage will change both reference and detector diode bias currents by the same percentage. The only effect to be considered is the change in voltage drop across R8, R10, which will change by 10% providing a 4 degree C temperature variation for the sensing of boiling and a 1 5 degree variation for the sensing of an empty kettle.

In the case of the temperature sensing diode SD1 intended to sense the boiling of water, the sum of the maximum temperature variations is as follows: offset voltage and error voltage to amplifier 5.7 offset current drift 0.0 5% resistor variation 5.1 diode-to-diode forward voltage variation 5.0 Supply Voltage variation 10% 4.0 Total 19.8 The maximum error in detected temperature will be about 20 degrees. Thus in the worst case combination of events the boil temperature comparator will switch at room temperature+39 degrees C+20 degrees C or at room temperature+39 degrees C-20 degrees C, which is within acceptable limits.

A similar analysis for the diode SD2 intended to sense operation of a dry kettle leads to the following: offset voltage & error voltage to amplifier 5.7 offset current drift 0.0 5% resistor variation 19.1 Diode to diode forward voltage variation 5.0 Supply Voltage variation 10% 15.0 Total 44.8 degrees C.

Thus in the worst case combination of events, the boil dry temperature comparator will switch at either room temperature+154 degrees C+45 degrees C. or room temperature+154 degrees C-45 degrees C, which is within acceptable limits.

For more precise control the circuits may be easily tuned by trimming the resistors R8, R10 in series with the sensing diodes SD1, SD2.

A reference voltage is generated by applying a biasing current of approximately 140 ,uA to a reference diode D5 using a resistor R5. This produces a forward voltage drop of approximately 530 mV in the diode D5. This voltage will track room temperature, varying inversely with ambient temperature and dropping by about 2 mV per degree C rise in temperature. Thus, the error voltages between the inverting and non-inverting terminals of the comparators OAl, OA2 will stay constant as room temperature changes, the changes in diode voltage occurring in D5 balancing that diode voltage changes occurring in the temperature sensing diodes SD1 and also SD2 to within about .1% Hence the comparators OAl, OA2 will tend to switch at a prescribed temperature difference between room and sensor Resistor R8 being 560 ohms will provide a voltage drop of approximately 78 mV.Thus when the temperature sensing diode SD1 is heated by 78 mV/2 mV per degree C or 39 degrees C plus or minus 20 degrees C above D5, the comparator amplifier OAl will switch from a O Volt output to 12.5 Volt output. This method of detecting boiling works over a wide range of temperatures, from about 95 degree C minus room temperature to 40 degree minus room temperature. The narrower the temperature difference, the shorter the period of time the kettle 10 will boil before the comparator trips.

The latter effect occurs when the water in the kettle boils and steam is generated in sufficient quantity that, upon condensing on the sensor SD1, the temperature of the sensor SD1 is raised by about 40 degrees C. above room temperature. When the water is not boiling, very little heat transfer will take place and the rise in temperature of SD1 will be insufficient to trip the comparator OA1.

Similarly with resistor R10 which has a value of 2.2 k ohms, the voltage difference between the inverting and non-inverting terminals of amplifier OA2, when the sensing diode SD2 and the reference diode D5 are at the same temperature, is approximately 0.14 ,tax0.22 k or 308 mV.

Thus when SD2 is heated by 308/2 or 154 degrees C above room temperature amplifier OA2 will switch from a low output voltage to a high output voltage. It should be noted that SD2 is bonded thermally to the kettle base at point near the heating element and its temperature should not rise by more than 100 degrees C during normal boil cycles. However, if the kettle is dry, the sensor SD2 will be heated to more than 100 degrees centigrade above room temperature by the heating element and will trip the comparator formed by amplifier OA2.

The temperature at which the amplifiers OA1 and OA2 switch in response to boiling and dry kettle conditions can easily be adjusted by varying the size of the resistors R8 and R10, respectively. Increasing the resistors increases the temperature difference required to produce switching.

As mentioned above, the amplifier OA3 acts as a logical OR gate. If either of the amplifiers OAl or OA2 has an output signal with a logical high value, the non-inverting terminal of amplifier OA3 will be at a voltage level exceeding that of the corresponding inverting terminal which is biased by resistors R6 and R7 at about, one-third of the supply supply voltage or about 4.7 volts. If one of the comparators OAl, OA2 has a logic high value, then the non-inverting input terminal of the amplifier OA3 will be at a voltage of about one-half of 12.5 V or 6.25 V, and the resulting voltage difference between the inverting and non-inverting terminals about 1.4 V will drive the output terminal of amplifier OA3 to about 12.5 V.As described more fully below, switching circuitry which regulates the application of power to the heating element responds in such circumstances by discontinuing the application of power to the heating element (the switching circuit otherwise responding to a logic low value by assuming a conductive state in which the heating element is operative.) The circuitry comprises a latch formed in a conventional manner by cross-coupling IC NOR gates NOR1 and NOR2. The purpose of the latch is two-fold. First, the latch forces the output signal generated by the operational amplifier OA3 once reaching a logic high value to remain at the logic high value. This is achieved by applying the logic high output signal generated in such circumstances at the output terminal of the gate NOR2 to the non-inverting terminal of the amplifier OA3.Since power is not applied to the heating element, the kettle 10, once it has been turned off in response to either water coming to a boil or the kettle being operated in a dry state, remains off. In either case, the relevant one of the sensing diode DS1 and DS2 would tend to cool and the heating function otherwise tend to be reinitiated. The latch also start a timer which operates an electronic buzzer or whistle (described more fully below) for about limited time period, indicating that one of the two shut-off conditions has occurred.

The latch is cleared or reset upon the removal of AC power when the kettle is unplugged or upon pressing of a reset switch SW1 when it is desired to commence another boil cycle. A diode D9 is provided to ensure that current cannot flow from the output terminal of an output terminal of NOR gate NOR4 to the output of NOR gate NOR3, formed as a common IC with the other NOR gates, via input clamp diodes on NOR4, eliminating contention and circuit misfunctioning.

The operation of the latch is delayed to accommodate uncertain conditions and output signals from the operation amplifier OA3 during powering up of the circuitry. A resetable lowpass filter is formed by a resistor R18, a capacitor C2 and a diode D6. The resistor R18 and capacitor C2 have a time constant nominally of about 0.47 seconds and constitute a delay circuit. These components in effect integrate the output signal generated by the operational amplifier OA3. As a result, the latching of the gates NOR1 and NOR2 is delayed for at least 0.5 time constants and possibly 4 time constants depending on the gate threshold voltage of gate NOR1.If at any time during the charging of the capacitor C2 to the threshold voltage required to trip the gate NOR1 the output voltage generated by the operational amplifier OA3 should return to ground potential, the capacitor C2 would abruptly discharge through the diode D6 (then forward biased) and the time delay would have to be reinitiated before latching. Hence, the output terminal of the operational amplifier OA3 would have to assume and remain at a high value for at least 0.25 sec before the latch comprising the gates NOR1 and NOR2 would set. This ensures that startup transients when power is first applied to the kettle 10 and the consequently uncertain state of the output terminal of the operational amplifier OA3 will not cause the latch to set and latch the heating function in an off state before proper of the kettle can begin.Since capacitor C2 is initially discharged, the latch will be initialised in a cleared state with the output terminal of the gate NOR2 at a low value.

The circuitry includes an audio oscillator which produces audible sound when water in the kettle 10 arrives at the boiling point. This oscillator comprises two IC NOR gates NOR3, NOR4, resistors R18, R19, a switch SW2 and a piezo ceramic audio transducer CR1. With the switch SW2 closed, the circuit operates as a conventional oscillator. The piezo ceramic crystal CR1 serves in such circumstances as an audio transducer and also a capacitor of approximately 20 nF for purposes of setting the frequency of oscillation. With the switch SW2 open, the audio oscillations cease. With the resistor values provided, and the noted capacitance, oscillation occurs at about 3 kHz. The duration of the audible sound produced is controlled by a timer described more fully below.

The timer is formed by an operational amplifier OA4, resistors R14, R15, R16, R17 and R20, and a capacitor C5. On startup, the state of the operational amplifier OA4 is undefined, but, since the various NOR gates are unpowered, the output signal generated by the operational amplifier is low and sound production is not effected. When the latch output signal (output of the gate NOR2) goes high, the voltage divider constituted by the resistors R14, R20 raises the inverting input terminal of the operational amplifier OA4 to about one-half of the supply voltage.

The non-inverting input terminal is at zero volts and hence the output is low. This causes the NOR3 and NOR4 to oscillate and results in an audible alarm. This alarm continues for about 10 seconds or one time constant associated with the resistor R15 and capacitor C3. When the non-inverting input terminal rises to a voltage level above the inverting input terminal, the amplifier OA4 switches to a high output voltage, turning off the oscillator. Resistors R16, R17 provide about 10% positive feedback or hysteresis to avoid any spurious switching in response to 60 Hz or power supply ripple which may create noise problems as the voltage differences between the inverting and non-inverting terminals approaches zero.

If the output terminal of the operation amplifier OA2 should switch high, indicating that the kettle is being operated dry, the non-inverting terminal of the timer operational amplifier OA4 rises to the supply voltage minus 1.5 volts thereby forcing the buzzer to operate for a relatively long period of time regardless of its initial state.

The primary switching component for regulating the application of line voltage to the heating element is a triac TR1, a bidirectional self-extinguishing switch which must be triggered in each half-cycle of the line voltage to remain conductive. The gate of the triac TR1 is connected by a resistor R21 to one of the AC supply lines to provide the required triggering signal.

A pair of transistors T1 and T2 which are either both conductive or both turned off serves to suppress the triggering of the triac TR1. When the output terminal of the operational amplifier OA3 is at a low value, the transistors T1, T2 are both off, and the triac TR1 is triggered in each half-cycle and delivers full power to the load. It should be noted that the transistors never experience a voltage greater than two volts across any jurictions of more and breakdown of the junctions is not expected. When the output terminal of the operational amplifier OA3 goes high, as in response to the kettle boiling or being operated dry, the LED D8 is activated to provide a visual indication of such condition and about 6 mA of bias current is provided to the bases of each transistor. During positive half-cycles of the AC line voltage, the transistor T1 is forwardbiased and the transistor T2 operates in inverted mode. This situation is reversed during negative half-cycles of the AC line voltage. The forward-biased transistor operates in saturated mode with a maximum collector current of 50 mA and a constant base current of 6 mA. The voltage across the transistor pair may typically be under 100 mV at a collector current of 60 mA for transistors with a high gain, at all times. Consequently the gate voltage on the triac TR1 cannot rise to an absolute 200 mV, the minimum required to turn on the device on the triac TR1 in high temperature operation. In such circumstances, the triac remains non-conductive and no power is applied to the heating element.

Appropriate values for the various circuit components illustrated will be apparent from the Table 1 below: Table 1 resistor R1 2.2 kilohms, 1.6 watts, Phiiips PR37 type, 20% tolerance resistor R21 3.3 kilohms, 3.2 watts, 2xPR37 in series, 20% tolerance resistor R2 160 ohms resistor R3 100 kilohms resistor R4 100 kilohms resistor R5 100 kilohms resistor R6 100 kilohms resistor R7 47 kilohms resistor R8 560 ohm, tolerance 5% resistor R9 100 kilohms resistor R10 2.2 kilohms, tolerance 5% resistor R11 2.2 kilohms resistor R12 2.2 kilohms resistor R13 4.7 megohms resistor R14 100 kilohms resistor R15 1.0 megohms resistor R16 100 kilohms resistor R17 100 kilohms resistor R18 16 kilohms resistor R19 8 kilohms resistor R20 100 kilohms resistor R22 100 kilohms capacitor C1 100 AF, 25 Volt electrolytic, 20% tolerance capacitor C2 0.1 ,uF, 15 V, metallized film cap, 20% tolerance capacitor C3 10 F, 1 5 V, electrolytic, 20% tolerance diode D1 1N4003 diode D2 Green LED diode D3 1N4148 diode D4 1 N4148 diode D5 1N4148 diode D6 1N4148 diode D7 iN4148 diode D8 Red LED diode D9 1N4148 transistor T1 2N4400 transistor T2 2N4400 triac TR1 15A RMS, 200 PRV Triac, TEECOR Q2012L5 OA1-4 LM324N, Quad opamp NORi-4 MC14001B Quad NOR gate transducer CR1 3 kHz, 1 inch Piezo Ceramic Audio transducer switch SW1 push button momentary contact switch, .1A, 15V switch SW2 SPST ON/OFF switch, slide or rocker type, .1A, 15V diode Z1 1N5244 Zener 14 Volts, +10% All resistors may be nominally rated at 1/4 watt types with 10% tolerance, unless otherwise indicated in Table 1.

It will be appreciated that a particular kettle has been described for purposes of illustrating various inventive features and the particular features of the kettle should not be regarded as necessarily restricting the scope of claims and the spirit of the inventive concepts embodied therein.

Claims (15)

1. A kettle having an electric heating element which is shut off automatically in response to high temperatures at a predetermined location in the kettle, characterized by: switching means for regulating the application of electric power to the heating element; a diode attached to the kettle proximate to the predetermined location; biasing means for producing a substantially constant current in the diode such that a diode voltage is generated which varies inversely with the temperature of the diode; means for causing the switching means to assume a non-conductive state in which no electric power is supplied to the heating element when the diode voltage drops below a reference level.

2. A kettle as claimed in claim 1 characterized in that the means for causing the switching means to assume a non-conductive state comprise: reference signal generating means for generating a reference signal corresponding to the reference level; and, comparator means for comparing the diode voltage with the reference signal and for generating a comparator signal having a predetermined state when the magnitude of the first diode voltages is less than the magnitude of the reference signal; the switching means responding to the predetermined state of the comparator signal by assuming a non-conductive state.

3. A kettle as claimed in claim 2 characterized in that the reference signal generating means comprise: a second diode attached to the kettle such that the second diode is normally exposed to ambient temperatures; second biasing means for producing a substantially constant current in the second diode such that a second diode voltage is generated which varies inversely with the temperature of the diode, the second diode voltage constituting the reference signal.

4. A kettle as claimed in claim 2 characterized by resettable latching means which respond to the predetermined state of the comparator signal by latching the switching means in the nonconductive state.

5. A kettle as claimed in claim 4 characterized in that the latching means comprise delay means for delaying latching of the switching means for a predetermined period of time from application of electric power to the kettle.

6. A kettle as claimed in claim 5 characterized in that the delay means comprise means for integrating the comparator signal and triggering the latching means to latch the switching means in the non-conductive state when the integrated signal exceeds a predetermined value.

7. A kettle as claimed in claim 5 characterized in that the latching means respond to the predetermined state of the comparator signal by applying a signal to the comparator means which tends to maintain the predetermined state of the comparator signal.

8. A kettle having an electric heating element which is shut off automatically when water heated in the kettle reaches a boiling temperature and when the heating element is powered without water, characterized by: switching means for regulating the application of electric power to the heating element; a first diode positioned for exposure to steam generated by water boiling in the kettle; a second diode positioned proximate to the heating element such that the heating element heats the diode to above the normai boiling temperature of water when water is absent from the kettle; biasing means for producing currents of substantially constant values in each of the first and second diodes such that first and second diode voltages varying inversely with the temperature respectively of the first and second diodes are generated;; comparator means for comparing the first diode voltage with a first reference signal corresponding to the boiling temperature of water and for comparing the second diode voltage with a second reference signal corresponding to a temperature substantially higher than the boiling temperature of water; the switching means being responsive to the comparator means and assuming a non-conductive state in which no electric power is supplied to the heating element when the first diode voltage drops below the first reference level or when the second diode voltage drops below the second reference level.

9. A kettle as claimed in claim 8 comprising: a third diode attached to the kettle such that the third diode is exposed to ambient temperatures; biasing means for producing a substantially constant current in the third diode such that a third diode voltage which varies in proportion to the temperature of the third diode is generated, the third diode voltage serving as both the first and second reference signals; the comparator means being adapted to compare the first and second diode voltages with the third diode voltage.

10. A kettle as claimed in claim 8 characterized in that the comparator means are adapted to produce a comparator signal having a predetermined state whenever the first diode voltage drops below the first reference level- or when the second diode voltage drops below the second reference level and the switching means respond to the predetermined state of the comparator signal by assuming a non-conductive state.

11. A kettle as claimed in claim 10 comprising resettable latching means which respond to the predetermined state of the comparator signal by latching the switching means in the non conductive state.

12. A kettle as claimed in claim 11 characterized in that the latching means comprise delay means for delaying latching of the switching means in the non-conductive state for a predetermined period of time from the application of power to the kettle.

13. A kettle as claimed in claim 12 characterized in that the delay means comprise means for integrating the comparator signal and triggering the latching means to latch the switching means in the non-conductive state when the integrated signal exceeds a predetermined value.

14. A kettle as claimed in claim 11 characterized in that the latching means respond to the predetermined state of the comparator signal by applying a signal to the comparator means which tends to maintain the predetermined state of the comparator signal.

15. A kettle substantially as hereinbefore described with reference to, or as shown in, the accompanying drawings.